The present invention relates to valves having adjustable seats and, more particularly, to damper valves having seats which are variably adjustable.
Damper valves of the butterfly type are known in which a blade, usually of circular shape, is mounted for pivoting between an open position and a closed position to control the flow of fluid through the valve. A shaft about which the blade pivots is positioned diametrically with respect to the blade and is mounted for pivoting in bearings beyond the periphery of the blade. A curved blade seat is positioned in a valve body for side, that is, axial, engagement with one of the faces of the blade along the periphery of the blade.
The blade, the seat and the body can all be made of stainless steel and can be fabricated with precision. However, during handling, shipment and installation of the valves, the body can deform slightly, especially since the valves are large, typically having a diameter of several feet. Even a slight distortion, for example, on the order of less than 0.0001 inch, can have an adverse affect on the sealing ability of the valve.